Means for mounting a thermostatic element



A ril 27, 1965 R. E. HERMAN 'MEANS FOR MOUNTING A THERMOSTATIC ELEMENT 2Sheets-Sheet '1 Filed May 8, 1962 April 27, "1.965 R. E. HERMAN3,180,576

MEKNS FOR MOUNTING A THEBMOSTATIC ELEMENT Fi'lsed May 8, 1962 2Sheets-Sheet 2 INVENTOR. RON/11 D t. ME/PMAA .Zbwi

ATTORNEY United States Patent O 3,180,576 MEANS FOR MGUNTING ATHERMOSTATIC ELEMENT Ronald E. Herman, Warren, Mich, assignor to HolleyCarburetor Company, Warren, Mich, a corporation of Michigan Filed May 8,1962, Ser. No. 193,252 Claims. (Cl. 236101) This invention relatesgenerally to internal combus- -tion engine carburetors havingthermostatically controlled automatic choke systems, and moreparticularly to novel means for relieving stress that may otherwisebuild up in the thermostatic element at higher engine temperatures whenthe choke is open.

Most carburetor automatic choke systems comprise a choke plate mountedon a shaft in such a way that the flow of air to the engine tends toopen the choke plate, and the openingof the choke valve is resisted whenthe engine is cold by the free end of a thermostatic coil spring havingits inner end anchored to the choke housing. In the usual case, the coilis unwound when cold and winds up when heated; thus, the resistance ofthe thermostatic coil spring to choke opening decreases as the enginetemperature increases.

The above described arrangement is generally acceptable. 'However, insome carburetor designs, it is essential that the choke housing comprisea compact shape, which in some instances is other than circular. In sucha housing, it is conceivable that the tang or free end of thethermostatic bimetal spring, after a certain amount of travel, wouldabut against a side of the choke housing, and thus not be free tofurther wind about its center as the temperature in the housingcontinued to rise.

Accordingly, a general object of the invention is to provide a means forstress relieving the thermostatic bimetal spring after it comes intocontact with the choke housing wall.

A more specific object of the invention is to provide a movable anchorwhich would permit the inner end of the bimetallic coil spring to rotateabout its axis in a direction opposite to the rotation of the externaltang, and

- thus relieve the stress that would otherwise be present in thebimetallic spring.

A further object of the invention is to provide for smaller chokehousings, or for housings which depart from 'a circular shape, thuspermitting a more compact configuration of thecarburetor and air-cleanercombination.

vention willbecome apparent when reference is made to' the followingdescription and the accompanying illustrations wherein:

FIGURE 1 is a front elevational view, with portions thereof cut away andin cross section, illustrating generally a carburetor embodying theinvention, the carburetor being mounted on the intake manifold of anengine;

FIGURE 2 is a side elevational fragmentary view of the carburetor shownby FIGURE 1;

FIGURE 3 is a cross-sectional view, taken on the plane of line 3''-3 ofFIGURE 1 and looking in the directions "of the arrows; i

FIGURE 4 is an enlarged, cross-sectional view of the automatic chokeassembly, taken on the plane of line 4-4 of FIGURE and looking in thedirection of the $18,576 Patented Apr. 27, 1965 FIGURE 5 is across-sectional view, taken on the plane of line 55 of FIGURE 4 andlooking in the direction of the arrows;

FIGURE 6 is an enlarged cross-sectional view, taken on the plane of line66 of FIGURE 4 and looking in the direction of the arrows;

Referring to the drawings in greater detail, FIGURE 1 illustratesgenerally a carburetor assembly 10 mounted on the engine intake manifold12. The carburetor 10 includes the usual carburetor body 14 with an airinlet passage 16 therethrough. The air inlet passage 16 includes theusual choke valve 18, venturi 20 and throttle valve 22. The choke valve18 is operatively connected to a bimetallic thermostat spring 24,positioned in the automatic choke housing 26, by means of the chokeshaft 28 and the choke lever 30. The choke housing 26 is warmed by airwhich enters the system through the air inlet passage 16 and then passesthrough a cold air intake 32 and cold air tube 34 to the exhaustmanifold 36 to become heated by a stove 38 located therein; the heatedair then passes through the hot air tube 49 and into the choke housinginlet 42.

FIGURE 2 illustrates the fast idle cam 44 pivotally fastened to thecarburetor body 14 by a fast idle cam -nected to a throttle lever 52which is responsive in the well-known manner through appropriate linkageto manual movement of the foot pedal (not shown). A throttle shaft 50 isfixedly attached to the throttle lever 52 for ro tation therewith inorder to actuate the throttle valve 22.

Maximum movement of the throttle lever 52 is controlled by the usualthrottle stop screw 54 which abuts against a lug cast on the side of thecarburetor body 14. Manual adjustment of the fast idle screw 48 and thethrottle stop screw 54 are maintained'by the compressed springs 58. Thecam 44 is operatively connected to the choke shaft 28 by means of a fastidle link 60, a linking element 61 and a set screw 62.

FIGURE 2 further illustrates the choke housing cover assembly 64 whichcomprises a choke housing plate 66, a thermostat cap and baffle assembly68, a thermostat cap clamp and a thermostat cap clamp screw 72.

FIGURE 3 illustrates the inner chamber 74 of the choke housing 26, withthe choke housing cover assembly 64 removed. The choke lever 30 is shownrigidly attached to the choke shaft 28'so that it can control theopening and closing of the choke plate 18. The choke housing chamber 74is subjected to vacuum from the intake manifold 12 through a vacuumpassage 76 and an inlet 78.

FIGURE 4 is an enlarged view of the complete automatic choke assemblydemonstrating the passageway 80 into the choke housing chamber 74 forthe hot air which enters the choke housing 26 through the thermostat capinlet 42. The choke housing plate 66 can be seen to include a gasket 82that may be cemented to its outer face that many carburetor designsutilize a single cover instead of the housing plate 66 and thethermostat cap and baflie assembly 68; in that event, the supportextension 86 for bimetallic thermostat spring 24 is attached to thesupport 3 extension 86. This View also demonstrates the cooperation ofthe thermostatspring tang 90 with the choke lever 39, and the subsequentcontact by the tang 90 with the choke housing wall 92.

With respect to the support extension 86, it can be seen that it amountsto a cylindrical stem being first formed with a pair of diametric, rightangle slots, the slots being as wide as the thickness of the spring 24and at least as long the the. spring 24 is wide so as to provide tour 90sections and then having a pair of oppositely disposed sections removed.The two remaining sections 87 and 89 adequately retain the inner end 91of the coil spring 24, but permit a 90 rotation thereof between thesections 8'? and 89 from the solid line to the dotted line portion D.

Operation have pivoted the fast idle screw 48 (FIGURE 2) away.

from whichever step of the fast idle cam 44 it was contact ing from theprevious operating of the vehicle. The cold bimetallic thermostat spring24' in the chamber 74, thus freed, would have immediately loosenedor'unwound itself with respect to the support extension. 86 so as toretate the choke lever in a counterclockwise direction to position A.The fast idle cam 44 would have been rotated by the fast idle link 6%leading from the choke shaft 28, which was also turnedby the coldbimetallic depression would then have allowed the fast idle screw 43 toreturn against the now rotated high step of the fast idle cam 44.

Referring again to FIGURE 6, as the warm air from the.

exhaust manifold 36 enters the chamber 74 through. the inlet-42 and thepassageway St) shown in FIGURES 4 and 5, the bimetallic thermostatspring 24 becomes warmed and begins to tighten about the supportextension Q 06, rotating in a clockwise direction, thus offering lessand less resistance to the opening of the unbalanced or offthermostatspring 24. Release of the initial foot pedal 1 higher temperatures is,effectively reduced or eliminated.

As stated previously, some prior choke designs have the tang 9t)actually looped about the lever 3%. Here, again, the spring 24 would bestressed at temperatures above the choke open temperature because thelever 39 is prevented from further clockwise rotation due to an abutmentwhich is necessary to prevent the choke plate from opening beyond thefully opened position.

Relieving stress in the thermostatic coil spring as d"- scribed above isimportant because the stress may exceed the elastic limit of the springmaterial so that a permanent set or deformation of a spring occurs. Thisset is in the direction such that it increases the resistance of thespring to choke opening when the engine is cold. Thus, the next coldstart would be either impossible or excessively rich. In other words,the permanently deformed coil spring would thereafter keep the choke ontoo long and adversely efiect cold starting and operation.

Thus, it can be seen that the invention enables the use of compact andirregularly shaped choke housings or the use of looped connectionsbetween the thermostatic coil spring and the choke lever, at the sametime relieving or eliminating harmful stresses that may otherwise existon account of such constructions.

Although but one embodiment of the invention has been shown anddescribed, it is conceivable that various modifications are possible,and no limitation not recited in the appended claims is intended.

What I claim as myinvention is:

1. In an internal combustion engine carburetor including an airinlet-passage, a'choke .valve in saidair inlet passage and means-torautomatically controlling the posi tion of said choke valve, saidmeans'including' a spiral type thermostatic element having a free outerend operatively connected to said choke valve and an inner end, said.outer end being restrained from further movement when a predeterminedtemperature has been attained, means for mounting said inner end so astoprovide a limited degree. of stress relieving motion thereof and.

when said outer end is restrained, said latter means comprising a pinhaving oppositely disposed wedge portions set choke plate 18 by thefresh air entering through the air inlet passage 16 (FIGURE 1). Thechoke plate 18 is thus progressively opened as engine temperature in.

creases until the choke lever 30 forces the thermostat springtang 9t: toposition B, at which time the choke valve 13 would be fully open. 7

Once the choke plate 18 is fully opened, the movement of the chokelever3tl, of course, will be stopped. Thereafter, however, dependingupon the thermal activity rate of the bimetallic thermostat spring 24involved, the spring 24 may continue to wind up. In fact, a typical highrate spring 24 would continue to wind about the center support structionwhere the inner end 91 of the coil is rigidly anchored, the aboverestraint-of tang 9i? of wall 92 would cause undue stresswithin thethermostatic spring 24 as long as the higher temperatures exist. g

It will be seen from FIGURE 6 that the invention eliminates the aboveobjections to present choke constructions, particularly in the smallercarburetor designs for the socalled compact vehicles. That is,'.thestructure of the support 86 for mounting the coil spring 24 issuchthatthe inner end 91 of the spring'is free to rotate 90 in a manterclockwise direction to the dotted-line position when tang 90 isrestrained by wall 92. Actually, the inner end 91 may begin to rotate inthe counterclockwise direction I once the tang 9% leaves contact withthe choke lever 30 '86 until its tang 9t) abuted against the chokehousing wall I 92, as shown at C. In the usual automatic choke conbetween which said inner end is mounted and the opposite alignedsurfaces of which provide'two limits of movement of said inner end.

2.iIn an automatic choke mechanism, athermostatic element having a freeouter end and a .pivotable' inner end formed thereon, means for heatingsaid thermostatic element, a pair of oppositely disposed wedge-shapedsupports, means for pivota bly connecting said :inner end to saidwedge-shaped supports, and means for at times restraining movement ofsaid free. outer end in one direction; one side of each of saidWedge-shaped supports serving torestrain' movement ofsaid inner end-insaid one direction while'said free outer end is moving in the samedirection, the-other twosides of each. of said wedgeshapedsupportsserving to restrain further movement of said inner. end in-theother direction after said inner end has moved a predetermined distance.

3. In an automatic choke mechanism including a choke shaft and a chokelever secured thereto, a spiral thermostatic'ele'ment having a 'freeradially-extending outer end and a dian retrically-extending inner endformed thereon, said outer end at times being in contact withsaid chokelever, means for heatingsaid thermostatic element, a pair of oppositelydisposed wedge-shaped supports, said inner end being positioned betweensaid wedge-shaped supports, means forrestraining movement ofsaid outerend in one direction after said outer end hasleft contactwith said chokelever, said inner; endbeingtree'to rotate from a position adjacent oneside offeach of said wedge-shaped supports toward the other sideoif eachof said wedgeshaped supportssonce said outerend leaves contact with saidchoke lever.

4.- In an automatio'choke mechanism including a choke shaft and a chokelever securedthereto, a spiral thermostatic element having aradially-extending outer end and a diametrically-extending inner endformed thereon, said outer end being in contact with said choke lever,means for heating said thermostatic element, a pair of oppositelydisposed wedge-shaped supports, said inner end being positioned betweensaid wedge-shaped supports, means for restraining movement of said outerend in one direction, said inner end being free to rotate from aposition adjacent one side of each of said wedge-shaped supports towardthe other side of each of said wedge-shaped supports with increasedtemperature.

5. A temperature-controlled mechanism, comprising a membert to bepositioned in accordance with temperature, a thermostatic spiral coilelement having the outer free end thereof operatively connected to saidmember and an inner end, means restraining the further movement of saidouter end as temperature increases, and rigid abutment means formounting said inner end in a manner to allow said inner end to assumeany position between two limits, said rigid abutment means including amounting pin formed to provide a pair of oppositely disposed wedgesections, the inner coil of said spiral coil element surrounding saidpin and said inner end being positioned between said wedge sections.

References Cited by the Examiner UNITED STATES PATENTS GEORGE D.MITCHELL, Primary Examiner.

HERBERT L. MARTIN, Examiner.

1. IN AN INTERNAL COMBUSTION ENGINE CARBURETOR INCLUDING AN AIR INLETPASSAGE, A CHOKE VALVE IN SAID AIR INLET PASSAGE AND MEANS FORAUTOMATICALLY CONTROLLING THE POSITION OF SAID CHOKE VALVE, SAID MEANSINCLUDING A SPIRAL TYPE THERMOSTATIC ELEMENT HAVING A FREE OUTER ENDOPERATIVELY CONNECTED TO SAID CHOKE VALVE AND AN INNER END, SAID OUTEREND BEING RESTRAINED FROM FURTHER MOVEMENT WHEN A PREDETEMRINEDTEMPERATURE HAS BEEN ATTAINED, MEANS FOR MOUNTING SAID INNER END SO ASTO PROVIDE A LIMITED DEGREE OF STRESS RELIEVING MOTION THEREOF AND WHENSAID OUTER END IS RESTRAINED, SAID LATTER MEANS COMPRISING A PIN HAVINGOPPOSITELY DISPOSED WEDGE PORTIONS BETWEEN WHICH SAID INNER END ISMOUNTED AND THE OPPOSITE ALIGNED SURFACES OF WHICH PROVIDE TWO LIMITS OFMOVEMENT OF SAID INNER END.